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Kari Palmer Clean Air Dialogues WG2
May 11, 2012
What is Ozone?
• A naturally-‐occurring consAtuent of the upper atmosphere protecAng the earth from UV radiaAon
• When formed at ground-‐level it causes human health and environmental problems
Health & Environmental Effects of Ozone
• High levels of ozone can have an adverse impact on the lungs • Airway inflammaAon, shortness of breath, coughing, aggravaAon of asthma, emphysema, bronchiAs
• Results in increased medicine use, doctor visits and hospital admissions
• ParAcularly older adults, children, people who exercise outside
• Damages vegetaAon, trees and crops
Trends in Ozone: Twin CiAes Metro, 1999-‐2011
0%
20%
40%
60%
80%
100%
120%
Percen
t of stand
ard
Standard
MN Ozone ConcentraAons (2009-‐2011)
60 59 59 58 62 61
63 60 60
65 63 62
58 54
49
62
0
10
20
30
40
50
60
70
80
Ozone
Con
centraAo
n (ppb
)
Standard
2011 Twin CiAes Air Quality Index Days Ozone
PM2.5
Ozone ConcentraAons Across the U.S., 2010
Ground-‐Level Ozone FormaAon in MN
• A chemical reacAon between nitrogen oxides (NO and NO2), oxygen, and volaAle organic compounds (VOCs)
• Sunlight fuels the reacAon -‐ at night ozone levels decrease
• Hot days above 85˚F
• Winds can transport ozone and precursors
Ozone
Ozone Chemistry • OH radical is central to
ozone and secondary PM chemistry
• OH iniAates reacAons of VOCs (and CO) that produce radicals
• Radicals interact with NOx (NO and NO2) in sunlight to form ozone
• Ozone requires both
NOx and VOC precursors
Ozone FormaAon
Ozone cycle disrupted by VOCS
VOC + OH = RO2 + H2O RO2 + NO = NO2 + RO
Normal ozone cycle NO2 + sunlight = NO + O O + O2 = O3 NO + O3 = NO2 + O2
June 6, 2011 Ozone Exceedance
June 6, 2011 Ozone Event Time Lapse
Hourly Ozone ConcentraAons Across Minnesota June 5-‐June 7
Locally Influenced Ozone Event 6/25/2009-‐6/27/2009
2008 Emissions of Ozone Precursors VOCs
• VegetaAon-‐55% • Miscellaneous-‐17% • Off-‐highway-‐8%
• Snowmobiles, boats, ATVs, etc.
• Highway vehicles-‐8% • Gasoline vehicles
• Solvent Use-‐7%
EPA NaAonal Emissions Inventory, 2008 version 2
Natural vegetaAon
55%
Miscellaneous 17%
Off-‐highway equipment
8%
Highway vehicles 8%
Solvent use 7%
Petroleum storage and tranport
2%
Other fuel combusAon
2% Other 1%
2008 Emissions of Ozone Precursors Nitrogen Oxides
Highway vehicles 39%
Off-‐highway equipment
23%
Fuel combusAon
from electrical uAliAes 15%
Metals processing
6% VegetaAon
6%
Fuel combusion industrial
5%
Fuel combusion
other 3%
Other 3% • Highway vehicles-‐39%
• Gasoline vehicles • Off-‐highway-‐23%
• Railroads, agricultural, construcAon and recreaAonal equipment
• Electric uAlity fuel combusAon-‐15%
EPA NaAonal Emissions Inventory, 2008 version 2
July 14, 2005
Area of ozone formaAon that is VOC-‐limited shrinks through the day
10 am 12 pm 4 pm
• Slide #19. Very Important! If you Atle this slide “What emissions decreases maoer”? Include the wrioen answer, “We don’t know”. And then say, the Agency uses photochemical models to simulate the complex processes in the formaAon of ozone and parAculate maoer. And as discussed earlier, these processes are intertwined. Largely we have focused our efforts on Regional haze, and now PM2.5, however, we did use photochemical models to look at ozone to help inform Clean Air Minnesota back in 2003, and in 2010 evaluated the processes of ozone formaAon for a few episodes in 2005. In this slide (and #20) you can see spaAally throughout one day how ozone formaAon is limited by the amount of available VOC in the urban area and how that shrinks throughout the day. The booom row shows how ozone formaAon is sensiAve to the amount of available NOx. This does not provide any definiAve answers on what to reduce but illustrates the process of ozone formaAon in Minnesota. NOTE: I don’t believe the bullet statements are correct.
July 14, 2005
Area of ozone formaAon that is VOC-‐limited shrinks through the day 10 am 12 pm 4 pm
What Emissions Decreases Maoer?
• We aren’t sure
• Photochemical modeling can help
MN Point Source NOX Emission Trends
0
25,000
50,000
75,000
100,000
125,000
150,000
2006 2007 2008 2009 2010
Tons
Other Pulp & paper Refineries Mining Electric utilities Manufacturing
Take Away Messages • Ozone causes serious health and environmental damage
• ConcentraAons are currently below standards and have been decreasing.
• Ozone chemistry is complex • Non-‐linear reacAons of NOx and VOCs
• Main sources are fuel combusAon • On and off-‐highway equipment,
• Electric uAliAes • Natural sources are important
• NOx and VOC reducAons may be important
Thanks to
• Cassie McMahon
• Margaret McCourtney
• Catherine Neuschler